Study On The Stability Of Soft-Weak Surrounding Rock And Initial Support In Unsymmetrical Loaded Tunnels

With the expanding of the underground construction projects, soft rock problem has been related to the transportation, electricity, and rural construction, mining and other fields, the stability of the soft and the support method has become the problem that needs to solve in underground work.This paper biases the actual support damage case in the soft rock tunnel to discusse the geological features and engineering features of the soft rock, the destruction of the characteristics of mechanical factors, deformation mechanisms, the principle of supporting and so on; The Interaction between surrounding rock and primary support is also discussesed mainly in this paper. Finding out the effect to tunnel stability from different strength of surrounding rock and support parameter has some guiding significance in complicated geological tunnel construction. The main contents and the major targets are as followings:①This paper biases the practical engineering situation in Taoshuya tunnel to discusse the geological features and engineering features of the soft rock, the destruction of the characteristics of mechanical factors, deformation mechanisms, and the principle of supporting.②This paper bias the monitoring measurement data in Taoshuya tunnel to analysis the deformation features and stability of the soft rock runnel and the primary support.③This paper is trend prediction with regression analysis to find the deformation trend of surrounding rock and the changing trend of support stress, then analysis the tunnel stability changing with time.④This paper discusses the interaction principle between the surrounding rock and surpport with analysising mechanism of shotcrete, radial bolt, steel support and mesh reinforcement, and then discuss the effect of surrounding rock deformation and force from roadway surrounding rock, support stiffness and initial support erection opportunity.⑤This paper analysises the cause of initial support failure and surrounding rock instability in Taoshuya tunnel, then analysises the effect of the tunnel and initial support in stability with different surrounding rock grade, bolt vertical spacing and joint angle.